Lancet Diabetes Endocrinol ; 6 8 : Equivalence was shown between low-activity 1·1 GBq and high-activity 3·7 GBq radioactive iodine and also between the use of rhTSH injections and thyroid hormone withdrawal. Here, we report outcomes after 5 years of follow-up.
Between March 28,and Feb 25,we randomly assigned adults with low-risk differentiated thyroid carcinoma who had undergone total thyroidectomy to one of four strategies, each combining one of two methods of thyrotropin stimulation rhTSH or thyroid hormone withdrawal and one of two radioactive iodine activities 1·1 GBq or 3·7 GBq.
Randomisation was by computer-generated sequence, with variable block size. Follow-up consisted of a yearly serum thyroglobulin measurement on levothyroxine treatment. Measurement of rhTSH-stimulated thyroglobulin and neck ultrasonography were done at the discretion of the treating physician.
This study was registered with ClinicalTrials. At ablation, six of these patients had received 1·1 GBq radioactive iodine five after rhTSH and one after withdrawal and five had received 3·7 GBq two after rhTSH and three after withdrawal.
TSH-stimulated either after rhTSH injections or thyroid hormone withdrawal according to the treatment group thyroglobulin concentration measured at the time of ablation was prognostic for structural disease status at ablation, ablation status at months, and the final outcome.
These data validate the use of 1·1 GBq radioactive iodine after rhTSH for postoperative ablation in patients with low-risk thyroid cancer.